Lars Bode, PhD, of the University of California in San Diego, and colleagues conducted a nested, case-control study involving 81 HIV-infected women who transmitted HIV to their infants through breastfeeding, 86 HIV-infected women who did not transmit HIV via breastfeeding, and 36 uninfected breastfeeding women in Lusaka, Zambia. The concentrations of total and specific HMO was measured and their association with the risk of postnatal HIV transmission was examined.

The researchers found that, after adjustment for CD4 count and breast milk HIV RNA levels, women with total HMO concentrations >1.87 g/L were less likely to transmit HIV via breastfeeding (odds ratio, 0.45). There was a trend toward higher levels of lacto-N-neotetraose being associated with reduced transmission (odds ratio, 0.49; P=0.06). Compared with non-transmitting women, transmitting women had a significantly higher proportion of 3'-sialyllactose per total HMO, which correlated with lower CD4 counts and higher plasma and breast milk HIV RNA viral loads. Transmission was not linked with Secretor or Lewis status.

"Epidemiologic and in vitro studies have shown that HMO protect infants from a wide variety of pathogens," the authors write. "Our study indicates that these versatile substances also play a role in protecting infants from HIV infection."